6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
commit 92cf7a51bdae24a32c592adcdd59a773ae149289 upstream.
As mentioned in the previous commit, using the 'net' structure via
'current' is not recommended for different reasons:
- Inconsistency: getting info from the reader's/writer's netns vs only
from the opener's netns.
- current->nsproxy can be NULL in some cases, resulting in an 'Oops'
(null-ptr-deref), e.g. when the current task is exiting, as spotted by
syzbot [1] using acct(2).
The 'pernet' structure can be obtained from the table->data using
container_of().
Fixes: 27069e7cb3d1 ("mptcp: disable active MPTCP in case of blackhole")
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/67769ecb.050a0220.3a8527.003f.GAE@xxxxxxxxxx [1]
Suggested-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/20250108-net-sysctl-current-nsproxy-v1-3-5df34b2083e8@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mptcp/ctrl.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 81c30aa02196..b0dd008e2114 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -160,7 +160,9 @@ static int proc_blackhole_detect_timeout(const struct ctl_table *table,
int write, void *buffer, size_t *lenp,
loff_t *ppos)
{
- struct mptcp_pernet *pernet = mptcp_get_pernet(current->nsproxy->net_ns);
+ struct mptcp_pernet *pernet = container_of(table->data,
+ struct mptcp_pernet,
+ blackhole_timeout);
int ret;
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
--
2.48.0
